PopUp In Javascript

function Termspopup()
{
window.open("../Terms.aspx","mywindow", "menubar=0,location=1,status=1,scrollbars=1,resizable=0,width=400,height=500");
}

Java Script In .cs file

protected void linkbtnTerms_Click(object sender, EventArgs e)
{
Page.ClientScript.RegisterStartupScript(this.GetType(), "Confirm", "Termspopup();", true);
}

On Mouse Over In Asp.net Text box